Linn County, Missouri
A shallow water table limits basements on 99% of Linn County's mapped land, a higher share than 100% of US counties and the highest of 115 Missouri counties. Shrink-swell clay limits houses without basements on 83%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 3 flood losses here since 2016. 76% of homes were built before 1980, against 50% nationally; the median home dates from 1964.
Data as of October 13, 2026 · sources
expansive clay: shrink-swell limits slab homes
high water table: limits basements
in drought, October 13, 2026
of homes built before 1980
Soil under Linn County
| Expansive clay (limits slab homes) | 83.2% |
| High water table (limits basements) | 99.1% |
| Septic fields very limited | 99.5% |
| Clay swell (LEP, by area) | 7.0% |
| High-swell land (LEP 6%+) | 77.0% |
| Mapped soil | 397,568 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Armstrong | 35% | over 99% |
| Purdin | 13% | n/a |
| Lagonda | 7% | n/a |
| Winnegan | 5% | n/a |
| Fatima | 5% | n/a |
| Blackoar | 4% | n/a |
How we count · survey areas MO115 (2025-09-02)
What the numbers mean here
Clay swell averages a linear extensibility of 7.0% by land area here, and 77% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 83% of the mapped land.
On 99% of Linn County's mapped land, soil stays saturated within about 6 feet of the surface for part of the year, which is basement depth.
Rain over the 12 months to August 2026: 33.82 in, 6.30 in below the 1991-2020 average year of 40.12 in.
USDA rates 99% of the land very limited for septic absorption fields.
Drought
0% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 8 of the last 52 weeks; the most was 31.4% of its area, in 2 weeks, most recently on the March 31, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 0% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
3 flood losses since 2016, $9,195 paid. The worst year was 2019, with 3.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 0 |
| 2018 | 0 |
| 2019 | 3 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 40.12 in |
| 12 months to August 2026 | 33.82 in (-6.30) |
| 2025 | 34.06 in (-6.06) |
| Wettest year since 1895 | 2008: 58.62 in |
| Driest year since 1895 | 1901: 22.56 in |
| Days with 1 inch or more, normal at BROOKFIELD (7 mi away) | 11.4 |
Homes
| Housing units | 5,988 |
| Median year built | 1964 |
| Built before 1980 | 76% |
| Built 2000 or later | 10% |
| Owner-occupied | 79% |
| Median value, owner-occupied | $123,300 |
| Single-family detached | 85% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Sullivan County, MO | 24 mi | 82% | 61% |
| Livingston County, MO | 24 mi | 76% | 98% |
| Chariton County, MO | 25 mi | 66% | 88% |
| Macon County, MO | 29 mi | 80% | 95% |
| Grundy County, MO | 30 mi | 75% | 78% |
| Adair County, MO | 35 mi | 68% | 95% |
| Carroll County, MO | 37 mi | 72% | 88% |
| Putnam County, MO | 43 mi | 76% | 74% |
Sources: USDA SSURGO (September 2, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status